Help in selecting low RPM motor

Help & Support Robot Parts
1

I don’t know if this is the right place for this question, anyway here it is:
I need a motor to be used as a generator to light a small lamp, or a led.
But the motor must give out “high” voltage at low speed and have low torque… :blush: I don’t even know if it is possible.
I have a small waterfall in my garden, just 10 cm high. I remember 10 or 15 years ago I was able to connect a motor to a wheel moved by the waterfall, and it was enough to light a small lamp.
Now I am no more able to recreate that project! All motors I tested are not able to produce enough power.

I counted the revolutions of the wheel: they’re relly a few, like less than 2 round per seconds, which means just 100 rpm!
Can anybody suggest the proper combination of motor and light source?
Any specific site for “small hydro power plants”? :confused:

2

We offer some hydro generators for faster running water, ex:
robotshop.com/en/seeedstudio … =RB-See-99

If you want a waterwheel approach, the following might work with some modifications:
robotshop.com/en/bicycle-dyn … RB-See-266

It sounds like the water simply isn’t moving faster enough or with enough force to be a good power source.

3

What about wind generators? They should require less torque. Anyone available, without buying the whole toy…?

4

You’d be looking for a dynamo like this:
robotshop.com/en/bicycle-dynamo-6v-3w.html
Remove the shaft cover and connect it to something that will rotate.

5

Already tried with a bycicle dynamo, it can’t light leds neither ultrasmall bulbs.

6

Note that the power output will always be a fraction of the power input due to inefficient in the system. You therefore need a way to provide power which would be greater than what you want to run. For example your small waterfall will likely not be able to provide more power than the pump which is used to run it, and the output from the dynamo or generator will only be a small fraction of this power. Small toy wind generators like the one you linked to require a good wind speed before they are able to provide power (voltage and current) sufficient enough to light up an LED or charge a small 3.7V battery.